Gauge cluster/wiring issue

[Oakland Bronco]

Before my Bronco burned up, the Alt gauge would constantly "bounce" while driving. +30/-30/+30/-30...constantly moving and really fast.

I now have a new Centech harness. With the exception of the engine block, heads, and steering box, everything in the engine bay has been replaced with new parts. The old stock gauge cluster was replaced with a different, refurbished stock gauge cluster......AND......the Alt gauge bounces just like it used to.

Interestingly, the left-turn signal indicator didn't work on the old gauge cluster, and isn't working on the new cluster.

Stock steering column. Column wiring issue maybe? Thoughts/suggestions?

I should add that, in the past, there were a couple of times when I engaged the turn signal, and the radio cut out. Also, all of the aftermarket gauges and knobs that a PO added were removed and no new aftermarket gauges/knobs have been installed.

 

[70_Steve]

Do you still have the old electro-mechanical voltage regulator? The one with the relays inside? You might consider swapping out to a solid state voltage regulator. 78 Granada is the only application I seem to remember...

Or, upgrade to a 3G alternator, then your ammeter won't work!!! Problem solved!!!

 

[Moon's74]

X2 on the voltage regulator. Also check all your grounds. Make sure the engine is grounded to the body and the chassis. I had similar problems, not quite as bad, that went away when I strapped the engine to both the body and the frame.

Also not real sure what kind of wiring is hanging around based on your description.

 

[DirtDonk]

Some of those old ammeters just bounce too. They get old and loose whatever dampening was built in. Whether that was just a coiled clockwork spring, or some other method, some gauges are going to bounce no matter what you do.
You can usually test this by tapping the gauge with your finger. If it bounces just from light taps, it's damping factor is toast.

If it doesn't bounce with the tap test, then on to other things. Like they said, some regulators (and even some alternators) will cause this. But with that much swing, are your lights dimming and brightening all the time? I would think you'd see a flicker in the other electrical components at the same rate as the needle sweeping, if it was your charging system itself.
Both the headlights, and especially the dash lights will indicate this.
Sounds like you have a new alternator and regulator though. Which is no guarantee of anything anymore of course, but at least it's less likely for the new ones to be at fault.

Regarding the turn signal indicator, that's a strange one with a new harness. But it's getting it's signal from the front turn signal circuit. Not likely to be in the column, but either in the new harness (less likely) or the grounding point up front at the light (more likely) especially since the body was old, slightly toasted, then repainted partially (I think?). Or has there been no new paint at all, even under the hood?

Anyway, make sure the front signal is working well and is bright and consistent. If not, check the socket, clean the ground on the core support, and maybe even add a jumper wire to ground the core support to the fender skirt/wheel well or other point past the old rusty spot welds that hold the core support to the rest of the body.

Good luck.

Paul

 

[Steve83]

The ammeter doesn't use the ICVR, so any ICVR issue would have no effect on ammeter bounce. I'd sooner suspect the alternator VR - is it still an old-fashioned mechanical unit, or a modern electronic version? Is it thoroughly grounded to both the battery & the alternator case? This & the NEXT 4 show the stock wiring:



But my FIRST guess would be the battery terminals. Are they clean, tight, & properly-attached? Click this & read the captions:



Is the alternator case clean where it grounds to the engine? Is the engine's (or bracket's) mating surface also clean? Was the engine ever painted with the alt/bracket removed? If so, the paint between the alt & block should be removed.



The turn signal indicator circuit branches off the turn switch in the column, so that's probably why you kept that symptom. I'd test/repair/replace the switch.